The
movie starts off with a scene where a kid was told by his god-sister that
his mother killed his father after she found out that his father had an
affair with a woman and after that his mother killed herself. Then it
zoomed to a murder scene where a man was found murdered with multiple
stab wounds. After that a woman was killed and raped with a stick under
a bridge. Then a man was killed with his genital being amputated by the
killer. After that, a woman was killed in the park with her tongue being
cut out.

Tam (Aaron Kwok) stepped in to help investigate the case after his buddy
Fung Chak (Liu Kai-chi) called for his help. However, Fung Chak's superior,
Inspector Lo (Patrick Tam) didn't like Tam to intervene his investigation
on the murder cases. He instructed one of his subordinate to attack Tam
and warned Tam to stop investigating. At the same night, his buddy Fung
Chak was ran over by a car. He survived the accident and advised Tam to
stop investigating the cases.

After days and days of brain cracking, Tam finally uncovered the mystery.
He found out that the murderer must be a orphan (I don't know how he manage
to come to that conclusion). So he shortlisted the suspects and found
out that one of them is an orphan. However, she had a sister. (Yes, you
are right. The boy at the beginning of the movie is the killer.) He went
to find his sister and found out that she is actually her mother. She
was raped at young age but didn't know how to tell her son. So she created
a story and told him that his parents passed away.

Later on, she found out that he became more possessive of her. So she
had to break the news to him and he ran away from home. That was the last
she saw him. Little did she know that her little lie turned out to be
too difficult for him to accept. He started to kill people and make a
radio story out of his killing spree. He recorded all his killings in
his recorder. Tam went to the killer's house and ransacked through his
things. He found the recordings. He took it with him. Later, when the
killer came home, he found out that his things went missing and he went
crazy. He went to the hospital and kidnapped Fung Chak. He called Tam,
asking him to return him his cassettes.

When Tam reached there, after some confrontation, the killer shot Fung
Chak, killing him. He then committed suicide by shooting himself on the
head.